I am just ramping up using Scrivener, and need to access multiple projects on multiple platforms for this to work.

I went to open a Mac-created file on Windows 7 computer and received the attached message telling me that I needed to update Scrivener on Windows. When I go into Scrivener and ask it to update, it tells me it is the most current version.

It is possible that I am a) doing this incorrectly, or b) there is some problem with DropBox but both seem unlikely. Assitance appreciated.

Without converting back and forth between Version 2 and Version 3 files, you can't.

The developers explicitly state this. There are methods provided to convert the project file each time, but if this is something you need to do, you may find it easier to keep the old version around just for that purpose. This is the relevant section from the manual:

3.4.3 Saving Your Projects for Older Versions

As noted, once you have upgraded your project to the new format, it will no longer be directly accessible to Scrivener 2.x for macOS, or 1.x for Windows. However it is possible to save a copy of your project in a format that can be read with these older versions, and even later load the modiﬁed project back into v3 with minimal loss of new settings and features.

The procedure is simple, but it’s important to understand that you won’t be able to share the project directly. If you’ve been working through a medium like Dropbox, with all devices and collaborators sharing one single project, you will need to adjust your working habits slightly.

To save a copy of your project in legacy format:

1. Open the project you need to save, and use the File ▸ Export ▸ as Scrivener 2 Project… menu command.

2. Select a location to save the copy (if using the cloud, choosing your shared folder would be a good option here) and select a name for the project.

3. Click Save

This will create a completely new copy of the project in a format that can be edited freely by older versions of Scrivener. However, when you wish to load the project back into Scrivener 3.x, it will need to be upgraded once again.

This method will therefore require a little management of project ﬁles which will accumulate every time you switch versions—and it also means that with larger projects that take considerable time to fully save and upgrade, it may not be a feasible way of working at all. In such cases, it may be easier to keep a separate copy of the older version of Scrivener (which you are entitled to use and unlock with your version 3 serial number, if purchased directly from us) and simply defer upgrading the project to v3 until such a time that all machines that need to work with the project can read and work in that format.